With recent progress of digitization of video signals, video/audio devices have employed a plurality of video and audio formats, resulting in an increase of video/audio devices compatible with the plurality of video and audio formats. Examples of the video/audio devices include a video/audio reproduction device (hereinafter abbreviated as a reproduction device) such as a television receiver or a projector, a video/audio signal input/output device (hereinafter abbreviated as an input/output device) such as a set-top box for receiving a digital broadcast or a DVD (Digital Versatile Disk) recorder, and so on. In addition, new video and audio formats have continuously been proposed. Therefore, it is considered that the video and audio formats with which the video/audio devices are compatible will further increase.
Hereinafter, one or both of the video format and the audio format is simply referred to as a “format”.
The currently-used video formats include 480i, 480p, 576i, 576p, 720p and 1080i and so on, for example. Here, “i” represents an interlace, and “p” represents a progressive. The audio formats include AAC (Advanced Audio Coding), PCM (Pulse Code Modulation), AC3 (Audio Code number 3), Mpeg (Moving Picture Experts Group) and so on. However, all the video/audio devices are not compatible with all the formats.
Therefore, a device setting operation including the steps of comparing the format that can be output from the input/output device and the format that can be received and reproduced by the reproduction device, and setting the format to be used is performed when the input/output device is connected to the reproduction device and the video signal and the audio signal are transmitted from the input/output device to the reproduction device.
The device setting operation has a case where the usable format is determined by a user operation using a device setting menu and so on, and a case where the input/output device and the reproduction device automatically exchange respective information indicating the formats for transmission/reception to determine the usable format between the input/output device and the reproduction device.
When the plurality of formats are set as the usable formats as a result of the device setting operation, the format output from the input/output device is switched in some cases by a channel selecting operation, switching of a reproducing content or the like in the input/output device.
This occurs in a case described below, for example. 480i and 1080i are set as the usable video formats in the input/output device and the reproduction device. Moreover, video of one broadcast channel of television broadcasting is broadcasted in the video format of 480i. When a different broadcast channel is selected in such a state, the selected broadcast channel is broadcasted in the video format of 1080i. In this case, the video format of 480i output from the input/output device is switched to the video format of 1080i.
In transmission/reception of the signal between the conventional input/output device and reproduction device, however, it generally takes one to several seconds, which is long, from the channel selecting operation by a viewer to channel selecting processing and the switching of the format in the input/output device and then to display of the video in the reproduction device, when such switching of the format occurs.
FIG. 9 is a flowchart showing an operation of switching the format in the conventional video/audio signal input/output device and video/audio reproduction device.
In the case of broadcast reception, for example, when the viewer performs the channel selecting operation using a remote controller or the like, the input/output device firstly performs the channel selecting processing of the broadcast channel (Step S1). After inputting the broadcast signal, the input/output device detects the format of the video signal (Step S2), and switches the output format of the video signal (Step S3). After that, the input/output device starts the output of the video signal (Step S4).
The reproduction device receives the video signal from the input/output device and detects the switching of the format of the video signal (Step S5), and switches display resolution and adjusts a display position for displaying the video in the switched format (Step S6). Then, the reproduction device starts the video display (Step S7). As described above, a series of processing is performed by the plurality of devices. Therefore, it takes a long period of time from the channel selecting operation to the video display.
The above-described switching processing of the format may occur at all times not only when the channel selecting operation is performed but also when the format of the content to be reproduced is switched; for example, when reproduction of a medium such as a DVD that can be reproduced by the input/output device is started or when a content recorded in an HDD (Hard Disk Drive) is reproduced.
Therefore, the viewer must wait until the switching processing of the format of each of the input/output device and the reproduction device is completed every time the channel selecting operation and the switching of a view medium are performed, thereby preventing the smooth channel selecting operation and so on.
Patent Document 1 describes an image display device that performs format switching processing. In the image display device of Patent Document 1, display-related information included in a received digital signal is extracted, and the display mode is automatically set in response to the display-related information while the display mode is set according to a setting instruction by a user when the setting instruction of the display mode is provided by the user.
[Patent Document 1] JP 2006-108750 A